yep, been thru this myself. this is usually from overtightening the caps. with good orings, finger tight plus +/- a quarter turn is all you need.
#1 - be careful no metal shavings go down into the tappet hole!!!!
with good gloves on, get your fingers in there and see if it will twist out by hand.
if not, dab some PB blaster on the sheared thread area a few times, and let it set overnight.
try turning it out with your fingers in the morning....